Remembering Project Daedalus

by Paul Gilster on December 16, 2006

Centauri Dreams defers to no one in admiration of Project Daedalus, the 1970s-era starship design that emerged from the British Interplanetary Society. It’s a pleasure to see continuing interest in the craft, as witness Alan Bellows’ backgrounder about it on the Damn Interesting site. Daedalus was the first serious and thorough design for a starship, a robotic interstellar probe that would reach Barnard’s Star in about fifty years, moving at twelve percent of the speed of light.

Be sure to check the Bellows story for the overview. But let me fill in a little more background: The British Interplanetary Society, founded in 1933, used to meet regularly at London’s Mason’s Arms pub on Maddox Street, a setting that Arthur C. Clarke readers may recognize from his later collection Tales from the White Hart. Daedalus was designed by about a dozen scientists and engineers, many of its sessions occurring in pubs and similar venues. When I talked to Geoffrey Landis about Daedalus some years back, he was as bemused about this as I was, saying “Imagine designing a starship while you’re sitting around in a bar. I mean, that’s just an incredibly ballsy thing to do!”

So I always think about Clarke’s book and wonderful evenings in similar pubs in London when I hear about Daedalus. Those long bar sessions in the 70’s produced extraordinary work, including a propulsion system that would provide thrust for a staggering four continuous years using fifty billion pellets of deuterium and helium-3, burning 250 of them every second in its combustion chambers. Daedalus was gigantic in every dimension, including the demands it placed upon the society that built it. The project, said the BIS final report, “… fits naturally into the context of a solar system-wide society making intelligent use of its resources, rather than a heroic effort on the part of a planet-bound civilization.”

Which is why industrializing the Solar System itself seems a prerequisite. When we do fly our first interstellar probes, they’ll doubtless be of different design that Daedalus, but they’ll still take advantage of the good work that went into its concept. Project Daedalus: The Final Report on the BIS Starship Study, edited by Anthony Martin, was published in the Journal of the British Interplanetary Society in 1978 and is thus hard to come by. My own dog-eared copy is the result of a marathon copying session at a nearby engineering library, carefully spreading the oversized JBIS pages to get a good image while not hurting the tight binding of the old volumes.

Interesting stuff? You bet. I’m always referring to this 1 1/2-inch stack of printouts. The introductory page quotes Immanuel Kant: “On the basis of a slight assumption I have undertaken a dangerous journey, and I already see the promontories of new lands. Those people who have the resolution to set forth on this undertaking will enter these lands and have the pleasure of designating them with their very own names” (from Kant’s Universal Natural History and Theory of Heaven, 1755). Those ‘new lands’ include designing a shield for interstellar dust, evaluating nearby stars for planetary systems, creating robotic systems for onboard maintenance and a communications capability to bring the data home.

I count twenty-one papers in all, most of them highly technical yet utterly absorbing even today. As to Barnard’s Star, here’s a link to a story in these pages that covers Peter Van de Kamp’s apparent detection of planets around it, which led to the BIS’ interest in the star as a destination for Daedalus. Turns out the data were flawed, but we still can’t rule out planets below current detection limits. And it’s intriguing that red dwarfs like this one have climbed well up the scale of interest when it comes to possible rocky worlds in habitable zones.

I hope someone will publish a new edition of the Final Report because my photocopies are getting pretty ragged, not to mention well marked up with notes. It would be a nice testament to a dramatic and visionary idea carried out by people who wanted to produce realistic designs using near-term technology. Talk about stretching the limits of the possible. And as Geoffrey Landis notes, they did it in a pub!

Addendum: Tibor Pacher reports that the British Interplanetary Society makes the Daedalus Final Reportavailable on CD. This is good news indeed. Thanks, Tibor!

I first read about “Daedalus” in a 1979 book by Iain Nicholson on Interstellar Travel – had a gorgeous colour plate of Daedalus blasting away from Callisto orbit. A kid’s book from the same year also featured it, with even more dramatic renditions, and it was a feature in just about every book I had on advanced space-travel concepts from that time. I later discovered that T.A.Heppenheimer’s work on pulsed fusion had pretty much demonstrated that the original design would’ve been fried by the neutrons produced by D-D side reactions.

I’ve a few questions for details from the final report – what was the final mass breakdown of “Daedalus” – the stages, propellant mass, payload? Thrust for each stage? Expected exhaust velocity/specific impulse? Thrust duration? Hard details to find definite answers for, oddly enough, as the Web seems to be relying on a single source of dubious provenance. And I can’t find a copy of the report anywhere locally here in Oz either.

By chance I have the Nicholson book right here — it’s The Road to the Stars, published in the UK by Bridge Books. The plate in question is spectacular, as you say, and shows not only a Jupiter moon behind the departing craft but what appears to be a huge space station around the moon as well, presumably part of the helium-3 mining operation that would be needed to fuel Daedalus. Nicholson’s book inspired lots of wild imaginings back then and I still have a great fondness for it.

On the Final Report questions, let me dig around and come up with some answers later today. Some preliminaries: Off the top of my head, I recall 54,000 tons total, of which 50,000 tons were fuel, with a scientific payload of 450 tons. Thrust duration was two years for the first stage and slightly less for the second but I need to look up your other questions.

OK Adam, let me run some of this information past you, this particular bit from Alan Bond and Anthony R. Martin’s summary paper “Project Daedalus: The Mission Profile.” The baseline vehicle finally arrived at (after various alterations along the way) looked like this:

I’ve always had a fondness for the “Daedalus” design – the flat leading edge with erosion shield was rather at odds all the starship designs in the SF books. And yes it was “The Road to the Stars” – in a fit of puerile self-disgust I gave away a lot of my old books and ever since I’ve been reborrowing them from libraries and trawlling the old Bookshops. Another favourite illustration from that book was the Ark arriving at a terraformed planet. Very cool.

That reminds me of another interstellar tale, Joe Haldeman’s “The Forever War”, and its much belated sequel/s. In the first version of his tale the starships are powered by tachyon drives, which had been speculated about in the early 1970s as a ‘propellantless’ non-FTL drive. In the later ‘sequels’ he uses antimatter, the sine qua non of 1990s interstellar fiction. Haldeman wasn’t overly rigorous in his physics, but he told a damned good story about the effects of relativity on warfare across centuries and light-years.

About the same time as the first “Daedalus” design – single stage, 150,000 tons – G.Harry Stine published “Project Starflight” in the October 1973 “Analog”. His ‘Enzmann starships’ have featured here and there, thanks to Rick Steinbach’s paintings, but the resemblance to “Daedalus” goes deeper. They were also nuclear-pulse drives, tho ‘Orion’ style, and fuelled up from Jupiter too. They had to be as Stine fuelled them up with 12,000,000 tons of deuterium. His mass ratios were 100:1, with a delta-v of 0.6 c! He also wanted 1000:1 mass ratio undeccelerated precursor probes doing 0.6 c to scout out target systems. And all this was supposed to begin with the probes being built in the late 1990s, followed by 10 ship fleets of the manned starships over the next ~ 120 years.

A few problems arise because the 0.3 c cruise velocity meant an exhaust velocity of 0.13 c, which is unlikely for fusion pulse devices. Something like 0.04 c at best is more likely, thus a cruise speed of 0.1c. Also deuterium bombs would need massive anti-neutron shielding. Lithium-lithium fusion bombs might be more feasible and have the advantage of being over 3.5 times denser than frozen deuterium. Would have to be lithium-6 but it’s present at between 3.75-7.25% of natural lithium, unlike much rarer deuterium. And it’s also present in asteroids at 65 ppm, so much easier to mine.

A final point is that inspite of the preference of science writers to mine He-3 from Jupiter it is equally abundant in Saturn, Uranus and Neptune, all of which are much easier to mine. A gas-core nuclear ramjet would be needed to lift cargo to low Jupiter orbit with an unprecedented 30 km/s delta-v. Saturn requires just 15 km/s, Neptune 13 km/s and Uranus just 11 km/s, all of which can be achieved with good old solid-core reactors. Uranus seems to be nowhere nearly as turbulent as Jupiter, or even Saturn, and seems the logical choice. Saturn I prefer because of Titan, but that’s just me. Also scoop-ships which process the material in-situ then climb back to space make more sense than floating balloons which are at the mercy of the winds.

When I talked to Geoffrey Landis about Daedalus some years back, he was as bemused about this as I was, saying “Imagine designing a starship while you’re sitting around in a bar. I mean, that’s just an incredibly ballsy thing to do!”

What you have there is an insight into the British mind-set – we do most of our best thinking in pubs. Or at least it certainly feels like it at the time! :)

Thanks for the heads-up – I shall see what the inter-library loans system can obtain for me. I’ll bet the British Library has a copy or two …

The Daedalus concept was based on the electron-beam-driven inertial confinement fusion (ICF) concept introduced by Friedhart Winterberg around 1970 and peaked around the time of the BIS study. That means it didn’t last long. The reasons were primarily fuel pre-heat, but there were others. The successor concept, ion beam-driven ICF, lasted much longer, until the imploded wire Z-pinch succeeded in producing radiation powers so high they can, if scaled, produce implosion of a ‘pill’ of D-T to produce fusion. It now competes with lasers (the NIF). By any measure of technical merit, the Z-pinch should win out. For fusioneers, this is nostalgic; Z’s were the first fusion concept (the gas discharge type) and now the wire version is likely to succeed, far more likely than the behemoth Tokamaks (the ITER).

Wow! Thanks for the “update” James, from the horse’s mouth virtually. Do you really think Z-pinch is better than tokamak? It’s certainly more amenable to making into a realistic space-drive than the multi-kilotons of reactor structure needed for a tokamak or laser-driven fusion drive. Andrews Aerospace’s Mini-Mag Orion uses magnetic compression to drive a fission charge to criticality – a fusion version is a logical progression.

Another caveat about the basic “Daedalus” design I read is that the MHD induction ring for extracting some power out of the exhaust probably won’t work and an on-board reactor will be required instead. Needed that for the cruise mode so it’s no great drama.

Inspite of its flaws and limitations what “Daedalus” did was publicise realistic studies in interstellar travel in a way like no other before it. Ramjets stayed in SF throughout the 60s while real spaceflight was burgeoning, but “Daedalus” sprang into the public mind as spaceflight was put on the back-burner.

Adam’s earlier post reminds me that I have that October 1973 Analog around here somewhere. I need to dig it out and re-read the original article about the Enzmann starship concept, something we need to return to here.

I once had the Star Trek Chronology of Spaceflight… and gave it away in my foolish youth! The most dissappointing thing about that book wasn’t that the Chronology was ‘wrong’ versus later Trekiverse canonical works, that the near-term events didn’t happen (Moonbase by 1998?) nor that the really cool SuperWarp ships didn’t appear in the next movies. All of those things are true, but what really got up my nose was discovering that all the convincing pseudo-detail on the 21st century ships was so manifestly wrong once I learnt enough about interstellar rocketry. It really was ‘Treknobabble’ in the end.

I can see the likeness, but it’s actually a photon rocket which I’m sure you’ve seen in many Western renditions. I’ve seen paintings of photon rockets by Andrei Sokolov which are much the same. About the same time didn’t Bonestell paint ion-rockets for “Beyond the Solar System”?

I wonder what the first rendering of a ramjet was? In one of my old, old kids books (Usborne’s “Galactic War” c.1975) there was a “Daedalus” class probe, but derived from the first press-releases I suspect – it had no name and was a single-stage vehicle. The ramjet on the same page was pretty much a standard design.

Adam; Yes, Z-pinches are much better than tokamaks because they have no (huge)magnets. They’re also likely to achieve high yields in later versions because they scale well. Tokamaks, on the other hand, are low-beta, which means that the magnetic energy will always be large compared to the fusion yield.

If a vessel could capture charged cosmic ray particles from only one direction, how much force might this be expected to impart (on average) per square meter? Would it be significant (in comparison with a sail)?

Tokamaks, on the other hand, are low-beta, which means that the magnetic energy will always be large compared to the fusion yield.

Since fusion yield (power) has units of energy/time, but stored magnetic energy has units of energy, this is meaningless. If you mean fusion yield integrated over the time the reactor operates, then of course the fusion yield in an operational, ignited tokamak reactor will be many, many times the stored magnetic energy.

What you probably meant to say was that plasma energy is much lower than stored magnetic energy. This is what low average beta is all about. This is an economic concern, since you need bigger magnets to achieve a given power output.

BTW, don’t proponents of Z-pinch reactor concepts have to wave their hands vigorously about how they actually get the electrical pulse into the target assembly? Disposable one-shot conductors don’t seem very practical, given how little the energy from each shot is actually worth.

Paul: I mean that in addition to the energy stored in the static magnetic configuration, there is in addition the driven circulating transient current in the circumferential direction, which consumes power. And even superconducting magnets consume power in the refigerating ancillary equipment. As to the conducting elements connecting the Z-pinch to the power supply, that’s a real issue for the advocates to deal with, and I expect plasma guns will be used to assemble the connections to the wire arrays. This compares to the replacable first wall issue in tokamaks. If there’s one thing that 50 years of fusion research efforts have shown, it’s that fusion ain’t easy!

It should be remembered that while Larry claims to be in the ‘Stone Age,’ he is also one of the most plugged-in and prolific suppliers of tips, leads and other good information that I have ever worked with. Stone Age indeed!

Charter

In Centauri Dreams, Paul Gilster looks at peer-reviewed research on deep space exploration, with an eye toward interstellar possibilities. For the last seven years, this site has coordinated its efforts with the Tau Zero Foundation, and now serves as the Foundation's news forum. In the logo above, the leftmost star is Alpha Centauri, a triple system closer than any other star, and a primary target for early interstellar probes. To its right is Beta Centauri (not a part of the Alpha Centauri system), with Beta, Gamma, Delta and Epsilon Crucis, stars in the Southern Cross, visible at the far right (image: Marco Lorenzi).

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